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Electronic states and wave functions associated with orbital energy crossing
Author(s) -
Pople J. A.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560050823
Subject(s) - wave function , atomic orbital , singlet state , molecular orbital , physics , configuration interaction , electron configuration , orbital overlap , avoided crossing , homogeneous space , atomic physics , electron , molecule , quantum mechanics , excited state , mathematics , geometry
A simple two‐electron, two‐orbital model is used to discuss the electronic states and wave functions in molecules where orbital energies corresponding to different symmetries cross. According to this model, it is predicted that the triplet state has the lowest energy in the crossing region. If configuration interaction is used, the crossing of singlet total energy curves is avoided. It is also shown that the major features of the configuration interaction treatment can be reproduced by single‐determinant wave functions provided that the molecular orbitals are permitted to be complex.